How De-Ionization (DI) Works
De-ionization, (commonly referred to as DI), is a common process for producing ultra pure water. The DI filter is filled with resin beads, some with a negative charge and some with a positive charge. When you test your water with a TDS meter (total dissolved solids), it gives you a number that tells you the sum of the different contaminates in your water. All of these contaminates are either negatively or positively charged, so when they pass through the DI filter they are attracted to the oppositely charged resin beads. Since the DI filter has both negatively and positively charged resin beads it is able to remove 99% of the contaminates in your water. Reverse Osmosis (RO) is capable of removing 95-97% of all contaminates, so when the remaining 3-5% is passed through a DI filter you are effectively removing 99.9% of the contaminates. This quality of water is comparable to distilled water and is excellent for use in reef aquariums and other application where distilled water is used.
Is It Safe To Drink DI Water?
DI water is 99% pure water, comparable to distilled water, so it is just as safe to drink as distilled water is. Due to the fact that it is so pure, a lot of people do not like the taste, so it’s potability (drink ability) comes down to your own personal opinion.
What is Reverse Osmosis?
Reverse osmosis is the finest form of water filtration known. The process allows the removal of particles as small as dissolved individual ions from a solution. Reverse osmosis is used to purify water and remove ions and dissolved organic molecules. It can be used to purify fluids such as ethanol and glycol, which will pass through the reverse osmosis membrane, while rejecting other ions and contaminants from passing. The most common use for reverse osmosis is in purifying water. It is used to produce water that meets the most demanding specifications that are currently in place. If two aqueous solutions of different salinity are separated by a semi-permeable membrane, osmosis will cause water to pass through the membrane in the direction of the more concentrated solution, therefore diluting it. By applying sufficient pressure to the more concentrated liquid, the direction of osmosis can be reversed. In this way, we can mechanically reverse the flow and separate the concentrated solution into its constituents: the water and the dissolved solids. One part is called the permeate, or filtrate, and the other is the reject stream, or concentrate.
How Does A Membrane Separate Substances?
Reverse osmosis uses a membrane that is semi-permeable, allowing the fluid that is being purified to pass through it, while rejecting the contaminants that remain. Most reverse osmosis technology uses a process known as crossflow to allow the membrane to continually clean itself. As some of the fluid passes through the membrane the rest continues downstream, sweeping the rejected species away from the membrane, in a concentrated brine reject water. The process of reverse osmosis requires a driving force to push the fluid through the membrane, and the most common force is pressure from a pump. The higher the pressure, the larger the driving force. As the concentration of the fluid being rejected increases, the driving force required to continue concentrating the fluid increases.
Reverse osmosis is capable of rejecting bacteria, salts, sugars, proteins, particles, dyes, and other constituents that have a molecular weight of greater than 150-250 daltons. The separation of ions with reverse osmosis is aided by charged particles. This means that dissolved ions that carry a charge, such as salts, are more likely to be rejected by the membrane than those that are not charged, such as organics. The larger the charge and the larger the particle, the more likely it will be rejected.